Treasurer Scott Morrison is under fire for using a controversial report to skewer Labor's negative gearing policy, after the report's authors clarified it was prepared before Labor's policy was announced and contained a crucial error.

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But the Treasurer's own homework has been shown up as somewhat lacking, after the report's author acknowledged it contained a key error and revealed the research was conducted "well before" Labor released its negative gearing plans.

"The assumptions were set several months ago, and the analysis done late last year, well before Labor announced its policy," BIS Shrapnel associate director Kim Hawtrey told Fairfax Media.

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Mr Hawtrey declined to say who commissioned the research but said: "I can confirm it is not a political party, or lobby group, or industry group. It is a private client."

Labor seized on an error, which appeared on the first page of the report and was repeated in media coverage on Thursday, that claimed Australia's national annual income was $190 billion - about the size of New Zealand's.

Grattan Institute chief executive John Daley rubbished the research, particularly its modelling on how higher taxes would affect land values. Mr Daley estimated the impact of Labor's policy on home prices would be closer to 2 per cent than the 6 per cent suggested by BIS, and said the report "did not pass the giggle test".

"Voters should be asking themselves whether a responsible government would rely on this sort of nonsense in a public policy debate," he said.

The report was welcomed by property lobbyists including the Real Estate Institute of Queensland, which put out an enthusiastic statement on Wednesday saying the research demonstrated any changes to negative gearing would be "disastrous".

But property researcher SQM questioned the findings, with director Louis Christopher saying the predicted 10 per cent increase in rents was especially "hard to believe".